Insulating material



April 9,v 1935. J. F. ALMER INSULATING MATERIAL Filed Nov. 25.

3 Sheets-Sheet l April 9, 1935.

J'. F. PALMER INSULATING MATERIAL 3 Sheets-Sheet 2 Filed NOV. 25, 1932 April 9, 1935. J, F, PALMER 1,997,389

INSULATING MATERIL Filed Nov. 25, 1932 5 Sheets-.Sheet 5 L1- 46 1( galla 16 2Q 1 y 70 ,Patented Apr. 9, 1935 1 UNITED STATESl PATENT oFEicE 19 Claims.

My invention relates to insulating material. More particularly my invention contemplates the fabrication of a multiplicity of cells of rubber which is substantially impervious to the passage 5 of moisture, air or other gases, particularly such as might be encountered in refrigerators orl the like. I am enabled to obtain a cellular structure formed of rubber which will have the necessary rigidity and resistance to distortion Aor collapse, and am also enabled conveniently and economically to fabricate such a structure by the use of a base or skeleton which is coated with the rubber. For example, by selection of unsized kraft paper and by spraying'it with latex, in fluid condition, the rubber of the latex compound will be deposited upon the kraft paper, and a portion, at least, of the moisture content will be readily absorbed by the paper and may be eliminated by a suitable dehydrating or`drying treatment. Other methods, however, of applying the rubber for the cell walls are available, as will be more fully pointed out hereinafter. Also, I point out in detail below the process by which my insulating materiahis completed. Y

My insulating material has been devised with refrigerator insulation especially in mind, although it-is by no means limited to that use.

Among the further objects of my invention are: The elimination of moisture migration which is a serious objection in insulating materials. Atmospheric moistureand moisture from the contents of a refrigerator is gradually absorbed by unprotected insulation. As determined by gravitation and also by the coldest regions where condensation is greatest, the moisture migrates and collects in certain regions-in refrigerators generally near' the bottom edges of side wall insulation. Here the insulation becomes soggy and musty and deteriorates. T'his moisture migration I eliminate by coating the paper frame or skeleton with latex. The latex coating is both waterproof and gas proof-particularly as to sulphur dioxide and methyl chloride and other common refrigerants. Preferably also the material is rendered non-conducive to vegetable or animal growth. These objects are `preferably secured bycoating the paper sheets constituting the insulating material with latex. While the primary purpose ofthe film or coating of rubber carried by the paper frame or skeleton is to form sealed rub- 'ber cellsgvit is an incidental but still very important result" that there is a moisture impervious barrier formed by the rubbeg between each sheet or ply of paper' at the points or regions where'they are adhered together or' lie together. This barrier prevents the migration of moisture from one paper sheet to another.

The elimination of separate coating materials and adhesive materials. 'This object I preferably secure by the use of a material such as latex which has the multiple function of moisture proofing, gas proofing, preserving and rendering the paper adhesive. v 1

Incorporating in the insulating material a mul tiplicity of small sealed air cells. In ceitain types of corrugated paper insulation heretofore proposed, the corrugations even if succeessfully sealed at their ends would be of considerable length. The cells being so relatively large, they are subject to considerable convection currents of the air therewithin. My sealed cells on the other hand are relatively small, and therefore intra-cellular air currents are correspondingly reduced, and the' insulating characteristic greatly enhanced. ,A

A multi-cellular insulating sheet whose surface can be internested with the', corresponding surface of another similar sheet, and especially where such internesting provides an additional set of sealed cells.

The foregoing, together with further objects. features and advantages of my invention are set forth in the following description of specific embodiments thereof and illustrated in the accompanying drawings, wherein: l l

Fig. 1 is a schematic perspective view of an apparatus for .producing the insulating material of my invention;

Fig. 2 is a fragmentary detailed sectionillustrating the apparatus for applying suction to the corrugations of the corrugating roll to corrugated paper pneumatically;

Fig. 3 is a perspective view of the corrugated side of a piece of a cellular sheet;

Fig. 4 is a plan view of the corrugated side of a small piece of multi-cellular sheet similar to that shown in Fig. 3, therespective edges of the sheet having been cut at various positions in respect to the corrugations, whereby the several edge elevations correspond to' various sections and the confusion of cross section lines in indicating typical cross sections is thus` avoided;

Fig.v 5 is an edge elevation of the piece of Fig. 4 looking along the line 5-5 of Fig. Land simulating across section across the primary or transverse corrugationsand intermediate the secondary or longitudinal corrugations;

Fig. 6 is an edge elevation of the piece of Fig. 4 looking along the line 6 6 of Fig. 4, and simulating a cross section parallel with the primary or transverse corrugations and at the valley thereof;

Fig. 7 is an edge elevation of the piece of Fig. 4

. looking alongv the line 'I-1 of Fig. 4 and simuare internested to form a double sheet and the double sheets are combined to form a block of insulation;

. Fig. 10 is another elevation of the block of Fig. 9 looking in the direction of the arrows Ill-I0;

Fig. 11 is a plan section taken on the lines II--II of Figs. 9 and 10 to show the relative disposition of the air cells in the multi-cellular sheets and the third set of cells formed when two such sheets are internested as in Figs. 9 and 10; and

Fig. 12 is an edge elevation of another block of insulation wherein the internested or double cellular sheets are assembled in a dierent relation to build up the block.

As an aid to understanding the structure of my `4insulating material, I shall first briey describe a method and apparatus whereby it may be produced. 'I'he apparatus schematically indicated in Fig. 1 will produce a continuous cellular sheet formed of two plies of paper. Kraft paper is suitable for the purpose.

For the purpose of illustration, in Fig. 1 I have disregarded proportions, reference being made to Figs. 3 to l1 inclusive therefor.

An upper paper sheet I5 is fed from a supply roll I6 by a friction faced feed wheel I6'. The underside of the sheet is coated with a thin film of latex from a spray I1. This maybe latex as 'it comes from the rubber tree concentrated to a one-third rubber content plus a preservative, if desired, but with rubber still in a colloidal form. The excess water content or surface moisture of the latex is largely absorbed by the uncoated 'kraft paper. 'I'his absorbs water content and the 'face of the roll I9. It has a manifold-like channel 29' which at .any moment engages the ends of the several passages I9' which correspond to the corrugations which are at -that time in contact with the paper. At intervals cross ducts 2| communicate between each passage I9' and the bottom of the corresponding corrugation. Suction is applied to the corrugation bottoms by the cross ducts 2|; the'passages I9', the channels 20' and the suction pipes 20": 'I'he bottomsand sides of each corrugation, the-end plates Nand the pa'" sheet I5 combine to fcrm a closed tubular chamnated the surface moisture from the latex coating, vthe paper has been rendered moist and warm. The moist paper `is better adapted for distortion by the corrugating roll. The meltingV point of rubber being about 248 F., the roll I8 should not be so hot as to subject the rubber film to that'high a temperature.

In the meantime a second-'or backing sheet-22 has beenfed from a supply 23, similarly sprayed withA latex on its upper side by the spray 24, dried by the drying roll 25 and brought over a platen roll 26 Aimmediately beneath the corrugating roll I9. The mating rolls 26 and I9 press the backing sheet 22 against the upper sheet I5 as it is corrugated, and the two are secured together by the adhesiveness of their latex coatings. The backing sheet 22 is fed by a friction faced feed roller 23 similar to the feed roller I6 for the upper sheet except the latter is larger in diameter. The rolls I9 and 28 together with the feed rolls I5' and 23 may be driven synchronously and at the same R. P. M., the larger diameter of the feed roll I1 taking care of the additional length ofl paper required for the sheet I5 because of its being corrugated.

, As the two-ply sheet is passed from the rolls I9 and 26, it consists of the backing sheet 22 untreated on its underside and 'latex coated on its upper side, and the corrugated upper sheet I5 superposed thereon. 'Ihe corrugated sheet is latex coated on its under side but not on its upper side. The outer sides of the two-ply sheet are thus non-sticky, and can be engaged by additional rolls for further operations without complicationsof working with tacky surfaces. The upper or corrugated sheet is adhered to the backing sheet along the bottoms of the corrugations by means of the latex coatings.

This two-ply transversely corrugated sheet is then engaged by a second set of rolls 28 and 29. The lower roll 29 is a plain platen roll. The upper roll 28 is circumferentially beaded or ridged at intervals as indicated at 30. The beads 30 of the roll 28, working against the roll 29, form spaced longitudinal corrugitions in the paper at right angles to the previously formed transverse corrugations. A bead is arranged at each end of the roll 28, so that the ends ofthe primary or transverse corrugations are sealed. The twoply corrugated sheet is then engaged by a second set of longitudinally corrugating rolls 3| and 32, the roll 3'I having a larger number of circumferential beads-33 than there are circumferential beads 30 on the roll 28. Preferably the number of beads 33 is a multiple of the number of beads 30 and preferably also certain of the beads 33 track the corrugations made by the beads 39.

The reason for effecting the secondary or long itudinal corrugations in two steps and for the above mentioned relation between the beads 39 and 33 will presently be described.

As the two-ply sheet passes from the rollers 3l and 32, its top is somewhat wallie-shaped or more precisely wallie iron-shaped, while the, back or underside is substantially flat. Both sides are then coated with latex by sprays 33 and 34 whence they are passed into a long drying chamber 35.

As it emerges from the drying chamber the cellular sheet may be cut to convenient lengths, and then appears as illustrated in Figs. 3 and 4` assupplemented by the cross sections of Figs.

5, 6, 7 and 8.

The lower sheet 22 is substantiallyA flat. The upper sheet I5 has primary or transverse corrugations 36 whose bottoms or valleys 35V are adhered to the back sheet 22 by the undercoating or latex rubber 31 on the sheet I5 and the upper coating 38 of latex rubberen the backing sheet 22. Superposed upon these transverse corrugations 36 are the secondary or longitudinal corrugations 39 eiected by the beads 36 and 33 of the rolls 28 and 3l.

vBecause the longitudinal corrugations 39 are made subsequent to the transverse corrugations 36, the result is one of crushing down the transverse corrugations 36 at the intersections 43 so that the cross section as seen in Fig. 8, for example, is like that of a box pleat. The folds 4I are -the result of the upper sheet I5 being of greater length than the backing sheet 22. The top surface of the upper sheet I5 carries a coating of latex rubber 42 while the bottom of the back sheet 22 carries a coating 43 of latex rubber. If, in the production-of my cellular sheetas previously described, the rollers 28 and 29 were omitted and all of the longitudinal corrugations 39 were formed simultaneously, the result would not be so desirable. 'Ihe formation of the longitudinal corrugations 39 considerably reduces the volume of the open-ended tubes initially formed by the transverse corrugations 36 and the backing sheet 22. If all of the longitudinal corrugations are formedsimultaneously, the volume of each open-ended corrugation tube is decreased by increments as the roll l3I passes over the corrugated sheet. Air within the tube displaced by this ensmalling of the volume passes out the ends. Bythe time the air cells 44 are sealed so that no more air can pass out the ends of the corrugation, the ensmalling of the volume has been substantially completed. v'I'he air trapped in the cells is at substantially atmospheric pressure at the moment. If the air has been above room temperature as a result of heat transfer held'over by the sheet from the dryingroll I8, the air may soon contract slightly, putting the cell under slight suction. In either case the'cell is not as resistant tocollapsing as though air under slight'pressure be trapped Within it. It is.

chiefly for this reason that I prefer first to seal lthe ends of the primary corrugations 36 against the loss of air before subdividing the corrugatons into the cells.

If I were to employ only the end beads 33 on .the nrst longitudinal roll 28, it would mean that al1 of the air thus sealed within the full volume of each tube formed by a transverse corrugation 36. would have to be distributed, asa result of the 4action of the roller -3I, among the several cells of the transverse corrugation. Because of the ensmalling effect of the longitudinal corrugations 39 on the Volume of the transverse corrugation tube, the aggregate volumes of the air cells 44 in any transverse corrugation 36 is con'- siderably less than the original volume of the corrugation 2. As a result the pressure would be l dangerously increased in the respective'v cells 44. There is a practicallimit to the internal air effected by the transverse and longitudinal cor-` rugations, etc. By initially subdividing. the transverse corrugations 36 into a. plurality of subtubes 45 by the rst longitudinal corrugating roll 26, I secure sealed sub-tubes whose internal pressure is substantially atmospheric pressure. This is because the sub-tubes 45 (Fig. l) are formed simultaneously and sealed by increments, so that the air displaced by the decreasing volume continues to pass out the end of the transverse corrugations 36 until the sub-tubes 45 are completely sealed.

Then byV subdividing the sub-tubes 45 into still smaller divisions or cells 44, I can raiserthein.- ternal air pressure of the individual air cells 44 considerably above atmospheric pressure, but

vstill not high enough to rupture the seal of the vantage of theinternal pressure in the'cells is` l that they hold the corrugated walls of the cells in position while the paper is still moist `from the latex spray, so that the paper dries in the proper shape.

' I hd that when using relatively light kraft roll 28 one and'one-half inches apart and using twice as many annular vbeads 33 on the second corrugating roll 3l so that in the finished cellular sheet the longitudinal corrugations are three-fourths oi an inch apart.

Using the multi-cellular sheet of Fig. 3 as a unit, a. plurality of such sheets may be assembled in any one of a number of relations to build the desired over-all thickness. For greatest insulation value per inch of thickness of material, I prefer the assembly relation shownin Fig. 9. In this the corrugated faces of two multicellular sheetsare placed together in internesting relation. The primary or transverse corrugations 36 vof the upper multi-cellular sheet of a pair run parallel with those of the lower multi-cellular sheet, but the sheets are oiset longitudinally one-half of the distance between corrugations 36 so that the ridges of the corrugations `36 on the upper sheet 1 come in the valleys of the corrugations 36 of the lower sheet, and vice versa. The upper cellular sheet is also offset transversely relativen? to the lower multi-cellular sheet by a distance Vequal to one-half of the distance between the longi` tudinal corrugations 39, as shown in Fig. 10. This results in a third set of transversely (I use the terms transverse and longitudinally as they were used in connection with Fig. l) disposed cells 46. I might explain that if `the transverse corrugations 36 only were used and there' were nov longitudinal corrugations 39, and the sheets were thus assembled, the corrugations wo d simply internest and there would be no third set of cells formed. The thirdv set of cells 46 is formed as a result of the longitudinal corrugations 39 and in general the aggregate volume of thejhird set of cells 46 is equal to the aggregate voluu'etric decrease in the corrugations 36 resulting from the longitudinal corrugations' 39. Thus while the use of the longitudinal corrugations 39 in subdividing the corrugations 36 reduces the aggregate cellular volume as far as the multi-cellular sheet itself is concerned, when two of these sheets arev combined as illustrated in Fig. 9, the lost volume is replaced, taking the iorm'ot the third set of cells 4,6. Y

As a matter of three dimensional geometry the outer conformatlons of the cells 44, when assemklio v cells 46 being substantially non-communicating.

The coatings 42 of sticky rubber serve to compensate for any inaccuracies of the internesting fit and to seal the third set of cells 46 from one another. This seal may be made still more perfect by placing the internested pair of multicellular cells between two parallel hot sheets which are spaced apart a distance equal to the thickness of the pair of intemested cellular sheets. 'I'he heat of the plates will raise the temperature of the air trapped within the several cells and press their walls tightly together. This being. done by internal pressure and not external pressure, there is no tendency to collapse the cells nor to lessen the thickness of the double sheet. It does, however, effect a better adhesion between the mating surfaces of the upper and lower cellular sheets and thereby better insures that the third set of cells 46 is substantially sealed against intercommunication and hence against transmission of heat by convection currents of air.

After the multi-cellular sheets have been inf ternested in pairs to Yform double units, the double units have substantially flat exposed surfaces represented by the respective backingA sheets 22. Two or more of these double units may be superposed as shown in Fig. 9. A block may be builtv up to'any desired thickness, the assembly being maintained by the adhesiveness of the rubber coatings 43 on the backing sheets 22.l

In Fig. 11 I have shown another way of assembling the multi-cellular sheets of Fig. 3. The corrugated sides are not internested in pairs, but instead the backing sheet 22 of one is laid upon the corrugated side of another sheet. In this way a block of any desired thickness may also be built up. I do not limit myself however to either of these two specific assemblies of the sheet of Fig. 3 into thicker blocks.

In practice when making sections or blocks of insulation for refrigerator walls, the continuous multi-cellular-sheet discharged from the apparatus of Fig. l may be cut into pieces of approximately the area of the desired section and the assembly indicated in Figs. 9 and 10 may be made with multi-cellular sheets of that size. When assembled to the desired thickness, the section may be trimmed as with a rotary knife. If desired the section may be wrapped with plain or latex coated paper before being set into position in the refrigerator wall. If the assembly shown Y in Figs. 9 and 10 be used, it is unnecessary to seal the edges of the section, and the paper wrapping is not necessary. If the section is not tobe Wrapped the outer surfaces may be dusted with talc to facilitate handling.

I prefer, however, to spray with latex the entire `exposed surface of a block of insulation material .after the respective multicellular sheets have been assembled, but before it is wrapped if it is to be wrapped. In this way I positively seal the block against the ingress or egress of moisture, air, gases, or odors even though there be unsealed interstices left especially between the backing plies of the multi-cellular sheets.

I contemplate that materials other than latex may be used for the coatings herein described. vif prefer to use late; for a number of reasons: It may be applied cold. AIt may be sprayed. The rubber is not affected by heat under 248 F. `making possible the use of steam heat in drying. This makes possible the use of my material in industrial insulating applications where temperatures would melt wax compounds for example. The insulation will not be deteriorated even by coming in contact with live steam. The rubber coating being unvulcanized, I take advantage of theremarkable stability of unvulcanized rubber as against the action of time,moist'ure, light, heat (within the limit specified) and most gases. Unlike vulcanized rubber, it is odorless. It contains no sulphur or other ingredient which might affect metal parts with which it comes in contact. It not only coats the paper but to anextent impregnates .the rbers. It is not conducive to mold or other fungus growths. The rubber is a good heat insulator. Its electrical insulating qualities make my insulation of advantage in heat insulating where poorly insulated electricalconductors are passed through it.

The several latex coatings 31, 38, 42 and 43 are initially adhesive and retain their tackiness for at least several weeks. This permits the consummation of `all'assembly operations within a reasonable time while still having the advantage of the adhesive qualities of the rubber coating.

In the course of time by incidental exposure the superficial surface of the coating will lose its tackiness, which is an advantage. However the rubber is not vulcanized and therefore will not deteriorate even on exposure to light.

While the rubber coating may .be applied as a.

solution or as a calendered sheet, itis a feature of my invention that the` rubberis applied as a spray or dip of latex wherein the rubber is in its natural colloidal suspension. This is more satisfactory and produces a better result than treating the paper with a form of rubber which has previously been chemically-coagulated to separate it from the water content of the latex or where the rubber has previously been substantially dried.

While I have disclosed these specific embodiments'of my invention, I contemplate that substitutions and changes may be made without departing from the scope of my invention. For assembly, instead of starting with plain sheets of paper and using the latex to adhere the corrugated sheet to the base sheet, one may start with commercial corrugated paper consisting of a base sheet and a corrugated sheet adhered together by the conventional silicate of soda. This corrugated sheet and backing may be dipped or otherwise coated with latex so that the inner surfaces of the tubes of the corrugations are treated, whereupon the longitudinal corrugations may be effected. The methods I have herein disclosed may be carried on more largely as hand operations, if desired. Instead of a continuous manufacture, lengths of sheets may be fed by hand to the corrugators. Also, instead of using a backing sheet which is flat, I may use one which is corrugated like the top sheet, so that the two sheets or plies constituting the multi-cellular sheet are duplicates and arranged with their low regions adhered together. In such case the cells are of substantially twice the volume and both sides of the multi-cellular sheet present corrugated surfaces which may be internested as previously described to build up blocks.

I claim:

1. A multiplicity of rubber envelopes each de ning an air cell therewithin and a paper frame to which the envelopes are xedly held in assembled relation.

2. A multiplicity .of rubber envelopes each de' iining an air cell therewithin and a paper frame substantially surrounding each envelope and between it and its adjacent envelopes.

3. An insulating material comprising a multiplicity of paper-framed rubber envelopes constituting a series of air cells.

4. An insulating material comprising a multiplicity of envelopes of unvulcanized rubber con'- stituting a series of air cells, each envelope being framed by stiffer material than the rubber lining the envelope.

5. An insulating material comprising a multiplicity of rubber envelopes constituting va series of air cells, the envelopes being intertted to form a further or secondary series of air cells.

6. An insulating material comprising a multiplicity of contiguously arranged rubber envelopes, each constituting. an air cell, with non-communicating intersticestherebetween, each envelope being framed by sheet material.

'7. A multi-tubular insulating sheet comprising l a pair of paper plies, one of which is corrugated and superposed on the other to form a. multiplicity of tubes, and a rubber lining for each tube.

8. A fabricated insulating material comprising rubber coated corrugated sheets in superposed assembly, the sheets being moistureproofed by, and adhered to one another in assembled relation by, the rubber coatings.

9. A cellular insulation comprising in combination sheets of material arranged to form air cells therebetween, and rubber coatings on the surfaces of the sheets for adhering them together in such arrangement; and constituting a rubber lining for each cell.

10. A multi-cellular vinsulating sheet comprising paper plies forming cells therebetween and a rubber lm lining for each cell.

11. A multi-cellular insulating sheet comprising in combination a paper base ply, a corrugated ply thereon, and a` coating of rubber on both plies 0n the sides thereof facing each other ply and ad hering the two plies together. 1

12. A multi-cellular insulating sheet comprising two plies of paper adhered together with air cells therebetween, the airin the cells being under positive pressure.

13. An insulating sheet comprising `a backing ply of paper and a corrugated ply of paper, the corrugated ply being corrugated both lengthwise and crosswise with the low regions of the corrugated ply sealed to the backing ply to form closed cells, and confined air within the cells under positive pressure.

14. An insulating material comprising a pair of multi-cellular'sheets, each sheeet comprising a backing ply and a corrugated ply adhered thereto, the corrugated ply having a series of parallel primary corrugatons therein and a series of secondary corrugatons imposed transversely upon the primary corrugatons and subdividing the latter into a multiplicity of air cells bounded by the backing ply and the corrugated ply, the two sheets being assembled with their corrugated sides together, the primary corrugatons of yone sheet being oiset relatively to those of the other sheet and the secondary corrugatons of one sheet being off- `set relatively to those of the other sheet whereby the corrugatons of the respective sheets intertogether, the primary corrugatons of one sheet being offset relatively to those of the other sheet whereby the corrugations of the respective sheets internest to form a third series of cells each cell of which is bounded by both corrugated plies.

16. An-insulating material comprising a pair of multi-cellular sheets, each sheet comprising a backing ply and a corrugated ply adhered thereto, the corrugated ply having a series of parallel primary corrugatons therein and a series of secondary corrugatons imposed transversely upon I the primary corrugatons and subdividing the latter linto a multiplicity of air cells, the two sheets being assembled with their corrugated sides together, the primary corrugatons of one sheet being oiset relatively to those of the other sheet whereby the corrugatons of the respective sheets internest to form a third series of cells each cell of which is bounded by both corrugated plies.

17. An insulating material comprising apair of multi-cellular sheets, each sheet comprising a' lbacking ply and a corrugated ply adhered thereto, the corrugated ply having a series of parallel n primary corrugatons therein and a series of secondary corrugatons imposed transversely upon the primaryl corrugatons and subdividing the latter into a multiplicity of air cells, the4 two sheets being assembled with their corrugated sides together and forming between the corrugated plies a third series of air cells, each having a volume of the order of the volume of the rst mentioned cells.

18. An insulating material comprising a pair-of multi-cellular sheets, each sheet comprising a backing ply and a corrugated ply adhered thereto, the corrugated ply having a series of parallel primary corrugatons therein and a series of secondary corrugatons imposed transversely upon the primary corrugatons and subdividing the latter into a multiplicity of air cells, the two sheets being assembled with their corrugated sides together and forming between the corrugated plies a third series of air cells each having a volume of the order of the volume of the rst'mentioned cells, the backing plies presenting substantially nat exposed surfaces. l

19. A fabricated insulating unit comprising a plurality of laminations or layers, each lamination comprising a pair of sheets formed with a multiplicity of air cells therebetween, and a lm of rubber between the laminations and extending over the area thereof, to check interlaminal migration of moisture, the laminations being adhered together as a unit.

JOHN F. PALMER. 

